Obesity Paradox in Heart Failure with Mildly Reduced Ejection Fraction

Objective: The study investigates the prognostic impact of body mass index (BMI) in patients hospitalized with heart failure with mildly reduced ejection fraction (HFmrEF). Background: Limited data regarding the prognostic impact of BMI in patients with HFmrEF is available. Methods: Consecutive patients with HFmrEF (ie, left ventricular ejection fraction 41-49% and signs and/or symptoms of HF) were retrospectively included at one institution from 2016 to 2022. Risk stratification was performed according to WHO -defined BMI groups. The primary endpoint was all -cause mortality at 30 months (median follow-up). Kaplan -Meier, uni- and multivariable Cox proportional regression analyses were applied for statistics. Results: 1832 consecutive patients with HFmrEF were included with a median BMI of 26.7 kg/m2 (IQR 24.0-30.8 kg/m2). Patients with lowest BMI (ie, 18.5-24.9 kg/m2) were associated with highest risk of all -cause mortality at 30 months compared to patients with higher BMI values (40.0% vs 29.0% vs 21.4% vs 20.9%; log rank p = 0.001; HR = 0.721; 95% CI 0.656-0.793; p = 0.001). Even after multivariable adjustment, higher BMI values were associated with improved survival at 30 months (HR = 0.963; 95% CI 0.943-0.985; p = 0.001). In contrast, the risk of HF- related rehospitalization at 30 months was not affected by BMI (log rank p = 0.064). Conclusion: In patients hospitalized with HFmrEF, lower BMI was associated with increased risk of all -cause mortality at 30 months, suggesting an obesity paradox in HFmrEF.